1. FIELD OF THE INVENTION
This invention relates to an improved fuel dispensing nozzle, such as that which is found at a service station to pump gasoline, and, more particularly, to an efficient vapor-proof seal and recovery system by which to reliably prevent the escape of hydrocarbon vapors into the atmosphere in accordance with air pollution abatement requirements.
2. BACKGROUND ART
A common feature of vapor recovery systems found in commercially available fuel dispensing nozzles consists of a flexible bellows or shroud surrounding the dispensing spout in a spaced concentric relationship therewith and extending from the body of the nozzle towards the dispensing end of said spout. The bellows or shroud forms an annular vent way between the bellows or shroud and the dispensing spout. The vent way extends through the nozzle body through a vapor return hose so as to return hydrocarbon vapors to an underground storage area. The sealing efficiency of the bellows-type vapor recovery system is effected by a sealing disk at the distal end of the bellows which sealingly engages the external lip of the fill pipe of a motor vehicle when the dispensing spout is inserted therein. The sealing disk is biased against the fill pipe lip by a helically wound compression spring that is disposed concentrically interior of the bellows and extended from the nozzle body to the sealing disk. The shroud-type seal is of identical operation, except that the seal is completed by the distal periphery of the shroud enveloping the radially outward portion of the vehicle fill pipe lip.
A mechanical or hydraulic interlock is usually provided to prevent the flow of gasoline until the vapor seal is completed. Also provided is a means for closing the vent way of the vapor return hose when the dispensing spout is withdrawn, thus preventing the escape of vapor from the underground storage area and into the atmosphere.
A means of attaching the dispensing nozzle to the fill pipe in the inserted and sealed position is also usually provided. Such provision commonly consists of a retainer ring secured to and extending radially outward from the dispensing spout. To engage said nozzle securing device, the operator must insert the nozzle spout into the fill pipe and past the engaging position, cock the nozzle spout out of concentricity, and then carefully release the nozzle until the retainer ring engages a radially inward extending portion of the lip of the fill pipe.
However, many of the conventional fuel dispensing nozzles are characterized as being relatively heavy and comprised of many component parts. Thus, the cost of manufacture and frequency of repair are undesirably maximized. In addition, the sealing efficiency of such conventional dispensing nozzles is sometimes unreliable so that hydrocarbon vapors will escape to the atmosphere whether the dispensing spout is inserted in or removed from the vehicle fill pipe. The engagement between the dispensing nozzle and the fill pipe is often ineffective due to the ware of the dispensing spout retainer ring or an unusual configuration of the fill pipe lip. What is more, the conventional dispensing spout is frequently plagued by premature shutoff due to increased back pressure at the spout.
Reference may be made to the following United States Patents for examples of various fuel dispensing nozzles having vapor sealing and recovery means:
______________________________________ 3,811,486 May 21, 1974 4,031,930 June 28, 1977 4,060,110 November 29, 1977 4,213,488 July 22, 1980 4,418,730 December 6, 1983 ______________________________________